@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700&display=swap');

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary-color: #0a4a3c;
    --secondary-color: #2d7a68;
    --accent-color: #5eb3a6;
    --light-accent: #a8d5cf;
    --warning-color: #f59e0b;
    --text-dark: #1a1f2e;
    --text-light: #6c7785;
    --text-muted: #9ca3af;
    --bg-white: #ffffff;
    --bg-light: #f7faf9;
    --bg-gradient: linear-gradient(135deg, #0a4a3c 0%, #2d7a68 100%);
    --border-light: #e5e7eb;
    --shadow-sm: 0 2px 4px rgba(0,0,0,0.06);
    --shadow-md: 0 4px 20px rgba(0,0,0,0.08);
    --shadow-lg: 0 10px 40px rgba(0,0,0,0.12);
    --shadow-xl: 0 20px 60px rgba(0,0,0,0.15);
    --max-width: 1200px;
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    line-height: 1.7;
    color: var(--text-dark);
    background-color: var(--bg-white);
    overflow-x: hidden;
}

html {
    scroll-behavior: smooth;
}

.container {
    max-width: var(--max-width);
    margin: 0 auto;
    padding: 0 24px;
}

/* Header and Navigation */
header {
    background: rgba(255, 255, 255, 0.98);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-bottom: 1px solid rgba(229, 231, 235, 0.5);
    position: sticky;
    top: 0;
    z-index: 1000;
    transition: var(--transition);
}

nav {
    padding: 1rem 0;
}

nav .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-brand h1 {
    font-size: 1.625rem;
    background: var(--bg-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    font-weight: 700;
    letter-spacing: -0.025em;
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 1.75rem;
}

.nav-menu a {
    text-decoration: none;
    color: var(--text-dark);
    font-weight: 500;
    font-size: 0.9rem;
    transition: var(--transition);
    position: relative;
    padding: 0.25rem 0;
}

.nav-menu a::after {
    content: '';
    position: absolute;
    bottom: -2px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--accent-color);
    transition: width 0.3s ease;
}

.nav-menu a:hover::after {
    width: 100%;
}

.nav-menu a:hover {
    color: var(--secondary-color);
}

/* Hero Section */
.hero {
    background: var(--bg-gradient);
    color: white;
    padding: 5rem 0 6rem;
    text-align: center;
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-image: 
        radial-gradient(circle at 20% 50%, rgba(94, 179, 166, 0.2) 0%, transparent 50%),
        radial-gradient(circle at 80% 80%, rgba(168, 213, 207, 0.15) 0%, transparent 50%),
        radial-gradient(circle at 40% 20%, rgba(45, 122, 104, 0.1) 0%, transparent 50%);
    animation: float 20s ease-in-out infinite;
}

@keyframes float {
    0%, 100% { transform: translateY(0) rotate(0deg); }
    50% { transform: translateY(-20px) rotate(1deg); }
}

.hero h2 {
    font-size: 3rem;
    margin-bottom: 1rem;
    font-weight: 300;
    letter-spacing: -0.03em;
    animation: fadeInUp 0.8s ease-out;
    position: relative;
    z-index: 1;
}

.lead {
    font-size: 1.25rem;
    opacity: 0.95;
    max-width: 650px;
    margin: 0 auto;
    line-height: 1.8;
    animation: fadeInUp 0.8s ease-out 0.2s backwards;
    position: relative;
    z-index: 1;
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* Content Sections */
.content-section {
    padding: 5rem 0;
    animation: fadeIn 0.8s ease-out;
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

.content-section.alt-bg {
    background: linear-gradient(180deg, var(--bg-light) 0%, var(--bg-white) 100%);
}

.content-section h2 {
    font-size: 2.25rem;
    margin-bottom: 2.5rem;
    background: var(--bg-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    font-weight: 600;
    text-align: center;
    letter-spacing: -0.02em;
}

.content-section h3 {
    font-size: 1.5rem;
    margin: 2rem 0 1rem;
    color: var(--secondary-color);
    font-weight: 600;
}

.content-section h4 {
    font-size: 1.25rem;
    margin: 1.5rem 0 1rem;
    color: var(--primary-color);
    font-weight: 600;
}

.content-section p {
    margin-bottom: 1.5rem;
    line-height: 1.8;
    color: var(--text-dark);
}

.content-section sup {
    font-size: 0.75em;
    vertical-align: super;
}

.content-section sup a {
    color: var(--accent-color);
    text-decoration: none;
    font-weight: 600;
}

.content-section sup a:hover {
    text-decoration: underline;
}

/* Overview Grid */
.overview-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
    margin-bottom: 3rem;
}

.overview-card {
    background: var(--bg-white);
    padding: 2rem;
    border-radius: 16px;
    box-shadow: var(--shadow-md);
    border: 1px solid var(--border-light);
    transition: var(--transition);
}

.overview-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.overview-card h3 {
    color: var(--secondary-color);
    margin-bottom: 1rem;
    font-size: 1.25rem;
}

.overview-card ul {
    list-style: none;
}

.overview-card li {
    padding: 0.5rem 0;
    border-bottom: 1px solid var(--bg-light);
    color: var(--text-dark);
}

.overview-card li:last-child {
    border-bottom: none;
}

.overview-card strong {
    color: var(--primary-color);
}

/* Safety Notice & Warning Boxes */
.safety-notice,
.warning-box {
    background: linear-gradient(135deg, #fef3c7 0%, #fed7aa 100%);
    border-left: 4px solid var(--warning-color);
    padding: 1.5rem;
    border-radius: 12px;
    margin: 1rem 0 2rem 0;
}

.safety-notice h3,
.warning-box h4 {
    color: #92400e;
    margin-bottom: 0.75rem;
}

.safety-notice p,
.warning-box p {
    color: #78350f;
    margin-bottom: 0;
}

.warning-box ul {
    margin-top: 1rem;
    margin-left: 1.5rem;
}

.warning-box li {
    color: #78350f;
    margin-bottom: 0.5rem;
}

/* Content Grid */
.content-grid {
    display: grid;
    grid-template-columns: 1fr 380px;
    gap: 3rem;
    align-items: start;
}

.content-main p {
    margin-bottom: 1.5rem;
    line-height: 1.9;
    color: var(--text-dark);
}

.info-card {
    background: var(--bg-white);
    padding: 2rem;
    border-radius: 16px;
    box-shadow: var(--shadow-md);
    border: 1px solid var(--border-light);
    position: sticky;
    top: 80px;
    transition: var(--transition);
}

.info-card:hover {
    box-shadow: var(--shadow-lg);
    transform: translateY(-2px);
}

.info-card h3 {
    background: var(--bg-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 1.25rem;
    font-size: 1.25rem;
}

.info-card ul {
    list-style: none;
}

.info-card li {
    padding: 0.75rem 0;
    border-bottom: 1px solid var(--border-light);
    color: var(--text-light);
    transition: var(--transition);
}

.info-card li:last-child {
    border-bottom: none;
}

/* Structure Details */
.structure-details {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    margin: 2rem 0;
}

.detail-card {
    background: var(--bg-light);
    padding: 2rem;
    border-radius: 12px;
    border: 1px solid var(--border-light);
}

.detail-card h4 {
    color: var(--secondary-color);
    margin-bottom: 1rem;
}

/* Benefits Grid */
.benefits-grid {
    display: grid;
    gap: 2.5rem;
}

.benefit-card {
    background: var(--bg-white);
    padding: 2.5rem;
    border-radius: 16px;
    box-shadow: var(--shadow-md);
    border: 1px solid var(--border-light);
    transition: var(--transition);
}

.benefit-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-xl);
}

.benefit-card h3 {
    color: var(--primary-color);
    margin-bottom: 1.5rem;
    font-size: 1.375rem;
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

/* Use Categories */
.use-category {
    margin-bottom: 3rem;
    padding: 2rem;
    background: var(--bg-light);
    border-radius: 12px;
}

.use-category h4 {
    color: var(--secondary-color);
    margin-bottom: 1rem;
}

/* Safety Grid */
.safety-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
    margin-bottom: 3rem;
}

.safety-card {
    background: var(--bg-white);
    padding: 2rem;
    border-radius: 16px;
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border-light);
    transition: var(--transition);
}

.safety-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.safety-card h3 {
    color: var(--secondary-color);
    margin-bottom: 1rem;
    font-size: 1.25rem;
}

/* Deposits Grid */
.deposits-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
    margin: 2rem 0;
}

.deposit-card {
    background: var(--bg-white);
    padding: 2rem;
    border-radius: 16px;
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border-light);
}

.deposit-card h4 {
    color: var(--primary-color);
    margin-bottom: 1rem;
    font-size: 1.25rem;
}

.deposit-card ul {
    list-style: none;
}

.deposit-card li {
    padding: 0.5rem 0;
    border-bottom: 1px solid var(--bg-light);
}

.deposit-card li:last-child {
    border-bottom: none;
}

/* References */
.references-list h3 {
    color: var(--primary-color);
    margin: 2rem 0 1rem;
    font-size: 1.5rem;
}

.ref-list {
    margin-left: 2rem;
    margin-bottom: 2rem;
}

.ref-list li {
    margin-bottom: 1rem;
    line-height: 1.8;
}

.ref-list a {
    color: var(--accent-color);
    text-decoration: none;
}

.ref-list a:hover {
    text-decoration: underline;
}

.ref-note {
    padding: 1.5rem;
    background: var(--bg-light);
    border-radius: 8px;
    font-style: italic;
    color: var(--text-light);
}

/* Legacy styles for compatibility */
.properties-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
    gap: 2rem;
}

.property-card {
    background: var(--bg-white);
    padding: 2.5rem;
    border-radius: 16px;
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border-light);
    transition: var(--transition);
    position: relative;
    overflow: hidden;
}

.property-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 4px;
    background: var(--bg-gradient);
    transform: scaleX(0);
    transition: transform 0.3s ease;
}

.property-card:hover::before {
    transform: scaleX(1);
}

.property-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-xl);
}

.property-card h3 {
    color: var(--secondary-color);
    margin-bottom: 1.25rem;
    font-size: 1.25rem;
    font-weight: 600;
}

.property-card p {
    color: var(--text-light);
    line-height: 1.8;
    font-size: 0.95rem;
}

.applications-list {
    display: flex;
    flex-direction: column;
    gap: 2.5rem;
}

.application-item {
    padding: 2.5rem;
    background: linear-gradient(135deg, var(--bg-white) 0%, var(--bg-light) 100%);
    border-radius: 16px;
    border-left: 5px solid;
    border-image: var(--bg-gradient) 1;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
    position: relative;
    overflow: hidden;
}

.application-item::after {
    content: '';
    position: absolute;
    top: -50%;
    right: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle, rgba(94, 179, 166, 0.05) 0%, transparent 70%);
    transition: var(--transition);
}

.application-item:hover {
    transform: translateX(8px);
    box-shadow: var(--shadow-md);
}

.application-item h3 {
    background: var(--bg-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    margin-bottom: 1.25rem;
    font-size: 1.5rem;
    font-weight: 600;
}

.application-item p {
    color: var(--text-dark);
    line-height: 1.9;
    font-size: 1.05rem;
}

.research-content {
    text-align: center;
}

.research-content p {
    margin: 0 auto 3rem;
    line-height: 1.9;
    max-width: 800px;
    font-size: 1.05rem;
    color: var(--text-light);
}

.research-topics {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: 2rem;
    margin-top: 3rem;
}

.topic-card {
    background: var(--bg-white);
    padding: 2rem;
    border-radius: 16px;
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border-light);
    transition: var(--transition);
    text-align: left;
    position: relative;
}

.topic-card::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100%;
    height: 3px;
    background: var(--bg-gradient);
    transform: scaleX(0);
    transition: transform 0.3s ease;
    transform-origin: left;
}

.topic-card:hover::after {
    transform: scaleX(1);
}

.topic-card:hover {
    transform: translateY(-6px);
    box-shadow: var(--shadow-lg);
}

.topic-card h4 {
    color: var(--secondary-color);
    margin-bottom: 1rem;
    font-size: 1.25rem;
    font-weight: 600;
}

.topic-card p {
    color: var(--text-light);
    font-size: 0.95rem;
    line-height: 1.7;
}

/* Footer */
footer {
    background: linear-gradient(135deg, var(--primary-color) 0%, #073a30 100%);
    color: white;
    padding: 3rem 0;
    margin-top: 6rem;
    position: relative;
    overflow: hidden;
}

footer::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 1px;
    background: linear-gradient(90deg, transparent, var(--accent-color), transparent);
}

.footer-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.footer-info p,
.footer-sponsor p {
    opacity: 0.95;
    font-size: 0.95rem;
}

.footer-sponsor a {
    color: var(--light-accent);
    text-decoration: none;
    font-weight: 600;
    transition: var(--transition);
    position: relative;
    padding-bottom: 2px;
}

.footer-sponsor a::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100%;
    height: 2px;
    background: var(--light-accent);
    transform: scaleX(0);
    transition: transform 0.3s ease;
}

.footer-sponsor a:hover::after {
    transform: scaleX(1);
}

.footer-sponsor a:hover {
    color: white;
}

/* Responsive Design */
@media (max-width: 1024px) {
    .nav-menu {
        gap: 1.25rem;
    }
    
    .nav-menu a {
        font-size: 0.875rem;
    }
}

@media (max-width: 768px) {
    .nav-menu {
        display: none;
    }
    
    .hero h2 {
        font-size: 2rem;
    }
    
    .lead {
        font-size: 1.125rem;
    }
    
    .content-section h2 {
        font-size: 1.75rem;
    }
    
    .content-grid {
        grid-template-columns: 1fr;
    }
    
    .info-card {
        position: static;
    }
    
    .overview-grid,
    .properties-grid,
    .safety-grid,
    .deposits-grid {
        grid-template-columns: 1fr;
    }
    
    .structure-details {
        grid-template-columns: 1fr;
    }
    
    .research-topics {
        grid-template-columns: 1fr;
    }
    
    .footer-content {
        flex-direction: column;
        gap: 1.5rem;
        text-align: center;
    }
}

@media (min-width: 769px) and (max-width: 1024px) {
    .content-grid {
        grid-template-columns: 1fr;
    }
    
    .info-card {
        position: static;
    }
    
    .properties-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}